Thursday, September 27, 2012

Weekend Front Brings Rain

By Jay Grymes & Steve Caparotta

Titan9 Doppler was picking up showers and even a few t-storms over the coastal parishes and into the greater New Orleans area today, a reflection of the increased moisture that has been building over our area. A few of those showers have made it into parishes just south of Baton Rouge as of 5 p.m.

Our thinking is that the low- and mid-level moisture will continue to increase over the viewing area into Friday and the weekend. After a partly cloudy night and some morning fog for Friday’s early commute, we’re expecting more clouds for the afternoon and adding in a 30% chance of rain for the afternoon and early evening. Friday’s high will be near 90°, and the additional humidity will give the afternoon a summertime feel.

But everything changes dramatically into the weekend as a southbound cool front interacts with a large disturbance over the region, keeping most of us “wet” for both Saturday and Sunday: NOT good news for LSU Tiger tailgaters!

The timing through the weekend and into early next week is still a little up in the air, but it looks like the front works through the state on Saturday into Sunday. The NWS Hydrometeorological Prediction Center (HPC) even indicates that a surface low will develop along the Texas Coast on Sunday and track eastward across southern Louisiana on Sunday into early Monday. If that scenario does evolve, Sunday could be as wet, if not even wetter, than Saturday. In addition, the rains could linger into the first half of Monday before the frontal complex exits to the east.

After the drenching many succumbed to during Isaac, it has been a fairly dry September for most WAFB neighborhoods. A little rain won’t hurt, and water levels along most area bayous and streams are low enough to be able to handle the wet weekend. The latest HPC regional forecast is suggesting widespread rains of 1.5” to 3.0” over the next five days. While we could see a few stronger t-storms over the weekend, we are not concerned -- at this point -- about any serious threats of widespread active or severe weather.

Nadine remains an active tropical storm (TS) in the east-central Atlantic -- ‘she’ has re-intensified a bit today, with 4PM max-sustained winds estimated at 60 mph. The National Hurricane Center 5-day forecast keeps ‘her’ at TS-intensity through the end of the month and into early October. Should Nadine make it through the 5 days as a tropical storm (October 2nd), ‘she’ will then have held onto TS or hurricane strength for 21 days, one of only a handful of Atlantic storms to survive that long.

Wednesday, September 26, 2012

Wet Weekend Ahead!

By Jay Grymes & Steve Caparotta

Today was yet another very warm, almost hot afternoon, with highs climbing into the upper 80°s for many WAFB neighborhoods.  That makes six straight days with highs in the upper 80°s to low 90°s, and our forecast calls for two more for Thursday and Friday.
Thursday shapes up to be a near repeat of today (Wednesday), although maybe a couple of degrees warmer.  For metro Baton Rouge, expect sunrise temps in the mid to upper 60°s with patchy morning fog and fair to partly cloudy afternoon skies with highs around 90°.  And as we’ve seen a couple of the past days, a spotty shower or thunderstorm can’t be entirely ruled out, but the vast majority of us will stay dry.
For Friday, the day begins much the same, and highs will return to near 90° for Friday afternoon, but we’ll also add in a 20% chance of afternoon rain.  So again, the vast majority of WAFB neighborhoods stay dry, but our Gulf humidity and a modest increase in atmospheric instability should allow for a few showers and rumbles of thunder across the viewing area.
Our forecast thinking has a quasi-stationary front aligned west-to-east across the eastern half of the nation.  Along the trailing end of that frontal system, we expect a slow-moving cool front to begin moving from the Southern Plains into the lower Mississippi Valley on Friday, with the front sagging into northern Louisiana by Saturday morning.  Rain chances will slowly but steadily increase from the latter half of the day on Friday into Saturday as that cool front approaches the WAFB viewing area.

But the front will be taking its time crossing the Bayou State, and that means “rain likely” for both Saturday and Sunday.  In fact, the current NWS Hydrometeorological Prediction Center (HPC) surface chart for Sunday shows a center of low pressure developing over SW/SC Louisiana on Sunday.  The front is expected to continue moving to the south and southeast and head out over the northern Gulf by Monday morning and then continue to move away from Louisiana into Tuesday.
The good news for the time being is that we are not especially concerned about widespread severe or active weather with this weekend’s frontal passage.  The latest HPC rain projections call for something on the order of 1.0” to 1.5” of rain for the viewing area and little or no pending threat of a severe weather outbreak.
And in the tropics, only Nadine is earning any attention today, and ‘she’ sure seems committed to hanging around for a while.  The latest NHC forecast keep Nadine at tropical-storm (TS) intensity into Monday.  If Nadine does survive into Monday, that will make 20 days at TS strength or greater!

Tuesday, September 25, 2012

Staying Warm & Dry

By Jay Grymes & Steve Caparotta

As was true today, modest mid- and upper-level ridging extending from the Southern Plains into the western Gulf will be enough to keep rain to near zilch and take highs up to around 90° for Wednesday and Thursday. At the same time, SE to southerly flow at the low levels will continue to provide Gulf moisture and keep dewpoints in the mid to upper 60°s.

While the forecast is not calling for days that are way above normal in terms of heat and humidity, we can expect a few more days that feel almost summer-like.

By Friday, we’ll introduce a slight rain chance to the forecast. Heading into the weekend, left-over moisture from the Pacific’s T.S. Miriam will combine with a mid-level disturbance and a slowly-advancing cold front to make for scattered to numerous rains for Saturday into Sunday. There is still a bit of uncertainty as to the timing of the rains and frontal passage through the weekend, but for now we’re thinking that the front slowly works through the state on Sunday and exits the region sometime Monday.

After the front pushes through, we should get a taste of moderately cooler and drier weather for the early part of next week.

In the tropics: T.S. Nadine just refuses to go away -- today is the 15th day that Nadine has maintained tropical/sub-tropical storm or hurricane intensity! The latest NHC forecast still calls for Nadine to complete a “closed loop” in her track by the end of the weekend into early next week. While Nadine’s peak sustained winds dropped into the 40s late last night, the NHC expects Nadine to re-strengthen in the coming days! Could it be that the Azores still aren’t ‘done’ with this storm?

Monday, September 24, 2012

A Return of Summer?

By Jay Grymes & Steve Caparotta

The good news is that we’ll stay mainly dry into the latter part of the week -- the bad news is that the front we thought might provide another round of fall-like weather failed to make it far enough south to have an impact. So we’ll be dealing with warmer-than-normal days through the work week and into the weekend.

An upper-level trough has set-up shop a little farther east than we had hoped. As a result, the surge of cooler, Canadian air that we thought would arrive over the past 24 hours or so also slipped off farther to the east, leaving us under the influence of an upper ridge centered over the Southern Plains. While this set-up does mean that we will continue to get a dry northwesterly flow aloft, sinking air from above and a warm, moist flow in off the Gulf will keep conditions warmer-than-normal and a bit humid through the rest of the week.

With light winds and dew points in the upper 60°s for each morning, patchy morning fog can be expected for each of the next few days, at least. In fact, some of that fog could be locally-dense, although not so widespread as to prompt a fog advisory.

Highs will climb into the upper 80°s to low 90°s, and with the humidity it will have a summer-like feel to the week, even though this is the first week of autumn.

We’ll be watching the development of a storm system in the Southern Plains by the end of the week, and the outlook for the weekend calls for decent rain chances. There remains a little uncertainty as to how the weekend weather will evolve, but for now we’re going with isolated to scattered rains for Friday, with higher rain chances for Saturday into Sunday.

In the tropics, we’re STILL watching T.S. Nadine as she continues to spin over the Atlantic. The latest round of forecasts suggests that Nadine could complete a loop over the east-central Atlantic, and the National Hurricane Center’s last discussion (10AM this morning) has Nadine still going strong five days from now!

If you are wondering, today marks ‘Day 13’ for Nadine. For the Atlantic Basin, the average length of time for a ‘named storm’ is only 6-7 days. Since 1851, there have been four systems to maintain “named strength” (ranked as a tropical storm, sub-tropical storm or hurricane) for 21 days or more, with a storm in 1899 lasting an amazing 27.75 days! 1971’s Ginger lasted 27.00 days, 1969’s Inga maintained tropical-storm or hurricane intensity for 24.75 days, and most recently, 2002’s Kyle persisted for 22.00 days. 

Thursday, September 20, 2012

Countdown to Autumn!

By Jay Grymes & Steve Caparotta

The autumnal equinox -- the official end of summer, or better said, the official start of the fall season -- occurs at 9:49AM on Saturday.  We don’t know about you, but we are more than ready for the coming weather changes!
Our forecast remains dry for the final official hours of summer; in fact, our current 7-day outlook is essentially rain-free for the entire period!

The winds are coming around, and we can expect flow off the Gulf with a slight increase in dewpoints over the next couple of days.  We will warm things up a bit over the next two days as well, with highs on Friday and Saturday in the upper 80°s to around 90°.  But the humidity levels will remain sufficiently low so as not to generate an “August” feel to the afternoons.
Our next front is still scheduled to arrive on Sunday morning and we still believe that it will be a “dry” front.  Sunday’s front may be a few hours slower than what we thought yesterday, but we still expect the front to push out into the coastal waters by Sunday afternoon.  Behind the front, we’ll enjoy another dose of cooler and less humid Canadian air.  We keep highs in the mid to upper 80°s for Sunday through Thursday, with morning lows in the upper 50°s to mid 60°s.
T.S. Nadine is still hanging around just south of the Azores!  The National Hurricane Center (NHC) suggests that Nadine will be losing her tropical characteristics in the next day or so, but the ‘post-tropical’ remains of the system could still be identifiable for another five days.  Meanwhile, the broad low between Nadine and Bermuda that we mentioned on Wednesday has started coming together, and the NHC now thinks that tropical or sub-tropical is likely in the coming days.  More problematic is the fact that the preliminary “spaghetti plots” have the system moving to the northwest over the next two to three days, and that could lead to a potential landfall threat for the Canadian Maritimes.

Wednesday, September 19, 2012

Beautiful Weather Continues!

By Jay Grymes & Steve Caparotta

Yes sir -- now that’s more like it!  A clear skies start with metro area temps in the 60°s for Wednesday morning ... and a sunny and mild afternoon with highs only reaching the low 80°s.  And the humidity?   Nada!

Well get even cooler overnight and early Thursday, with lows expected to dip into the low to mid 50°s for the Capital City -- some areas along and north of the LA/MS state line could dip to or even just below the 50° mark!  And Thursday should be just as pretty of a day as Wednesday, although maybe a few degrees warmer into the afternoon.
Surface high pressure that is currently the main driver for our local weather today and overnight will migrate to the east on Thursday.  By Thursday afternoon and evening, we’ll start to get a more easterly and southeasterly flow over the viewing area.  While the SE flow will mean a very modest return of Gulf moisture and warmth for Friday, Friday will still be a great day under fair skies.  Highs on Friday for the Red Stick will approach 90° -- very warm, but the humidity remains low enough to keep things reasonably comfortable, especially into Friday evening.
By Saturday, enough low-level moisture will have returned to keep morning lows in the 60°s and provide partly cloudy skies during the day.  At the same time, the SE flow will be enhanced by the approach of our next cool front from the north.  But for the time being, we just don’t think that enough Gulf moisture will build back into the atmosphere to support any significant rain as the front works its way through the Bayou State.
The current guidance suggests that the weekend front will push across the WAFB viewing area during Saturday-to-Sunday’s overnight and pre-dawn hours.  By the late morning to mid-day hours on Sunday, skies should be mainly sunny as we enjoy another surge of cool and dry Canadian air.  In fact, our extended forecast remains dry at least through the middle of next week!
In the tropics, a very persistent T.S. Nadine continues to spin to the southwest of the Azores Islands, and has been drifting for much of the day.  Forecasters still believe that Nadine will turn to the ESE in the next 24 hours or so, taking ‘her’ south of the Azores.

Elsewhere in the tropics, there are no areas of weather with an immediate threat of development.  The NHC is watching a broad, “non-tropical” low situated between Bermuda (to its west) and Nadine (to its east).  Currently the NHC gives this area only a low chance for developing into a tropical or sub-tropical system, but even if it were to acquire tropical characteristics, it offers no serious threat to any land masses.

Tuesday, September 18, 2012

Gorgeous Weather Rest of This Week

By Jay Grymes & Steve Caparotta

Did you notice?  Not a single day with measurable rain in our seven-day forecast!  That sure looks good to us!  Yep ... we are headed into the best time of the year for south Louisiana weather -- as long as the tropics cooperate, that is!

We’re still waiting for the skies to clear this afternoon, but clearing from the north and west will continue as the day progresses.  The winds over the Baton Rouge metro area have already swung around, indicating that the primary frontal energy has passed to our south and southeast.  But a secondary, weaker front is still stretched from central Mississippi into Louisiana where it’s southwestern end fizzles out.  Regional radars are showing some light, spotty showers along that secondary front that are headed towards southern Louisiana.  If they hold together -- and that looks like a big “if” -- a couple of area neighborhoods might get a sprinkle during the late afternoon or early evening, but essentially we’re done with the wet weather.  Skies will continue to clear this evening and later tonight.
Wednesday, Thursday and Friday should be great weather days.  Most WAFB viewing communities can expect morning lows for all three days in the 50°s.  Wednesday’s high will top out in the low 80°s, with highs easing to the mid 80°s for Thursday and the mid to upper 80°s for Friday.  But the humidity stays comfortably low for all three days.
Yesterday we were thinking isolated showers possible for Saturday as our next cool front pushes through, but we’ve got two changes to that thinking today.  First, the weekend’s front is looking like it will be a “mainly dry” passage, with little or no rain for any WAFB viewers.  And second, it looks like the front may arrive in the BR area a little later than initially thought -- possibly not until midnight or even in the pre-dawn hours Sunday morning. 
In any case, Saturday looks to be a little warmer than the prior weekdays, with a slight increase in humidity associated with the flow off the Gulf in advance of the front.  But there doesn’t look like there will be sufficient moisture available to generate any meaningful rains as the front moves through, and the set-up should deliver a fine looking Sunday afternoon with highs slipping back to the low to mid 80°s.
In the tropics: T.S. Nadine just keeps on hanging on and the forecast continues to call for ‘her’ to take a turn to the south later this week, which is great news for residents of the Azores Islands.  Elsewhere, there are no pending tropical waves or disturbances that show signs of development any time soon.  But remember, we’ve still got well over two months more of the official season to go (the end of November).

Monday, September 17, 2012

Turning Drier by Late Tuesday

By Jay Grymes & Steve Caparotta

Monday’s rains really weren’t all that bad, in that for many neighborhoods it has been dry since Isaac’s unwelcomed visit. While many areas received from 1” to 2” of rain through the day, so far we’ve not had any serious problems with roadways for the evening drive home.

A combination of a surface low near the coast and an upper-level low over SE Texas like we have today would normally be a real problem for us, but a “dry slot” has developed to our west, causing a tapering of the rains through the afternoon. We’ll keep scattered to isolated rains in the evening forecast, then go with mainly isolated rains in the overnight and early morning.

The tougher part of tomorrow’s forecast is what to make of the afternoon. For now, we’ll go with isolated showers in the early part of the afternoon with clearing underway by the late afternoon or early evening.

The current weather-makers -- the surface and upper-level lows -- will be moving to the east tomorrow, but at the same time our next cool front will be dropping southward through the state. So we’ll keep a slight chance of rain in the forecast as there could be just enough moisture still left from the pair of lows to fuel some afternoon showers as the front slides through the viewing area. In addition, it looks like the front will slow a bit as it moves through the southern parishes.

But once the front moves far enough south, skies should clear and we get a dose of notably cooler and less humid air, making for a couple of beautiful fall-like days for Wednesday and Thursday.

A brief warm-up will set-in for Friday into Saturday, but our next front arrives Saturday and delivers another shot of cool, dry continental air for next Sunday and Monday. Once again, we think that Saturday’s front will be a mostly dry passage, with only isolated showers.

We’re still watching Nadine as she continues to spin over the central Atlantic. While Nadine offers no immediate threat to land, residents of the Azores will remain on guard. Interestingly, Nadine may take a may turn back to the south before reaching the Azores.

Thursday, September 13, 2012

Hot, Drier for Friday & Saturday

By Jay Grymes & Steve Caparotta

Like Wednesday, we’re watching some showers and isolated t-storms roll across portions of the viewing area this afternoon ... but unlike Wednesday, none of the t-storms have prompted a Severe Warning thus far today. The rains should subside later this evening, giving way to mainly fair skies tonight.

Winds from the east and ENE over the next day will provide a very slight dip in humidity levels for Friday, not only making for a drier day than today but also providing a slight dip in the humidity. Don’t be confused, however ... this will not mean a return of the great weather from earlier in the week!

The front we’ve been talking about for the past couple of days will still arrive over the weekend, but the forecast now is for an even slower approach and an even more diffuse boundary than we had been anticipating. That means that Saturday looks like it will be a mainly-dry day too, with only spotty t-showers for the afternoon forecast -- and that’s great news for LSU Tiger tailgaters as LSU hosts Idaho on Saturday evening in Death Valley.

The front may start to fizzle out along the central Gulf Coast late Saturday into Sunday, but some of the extended guidance indicates that what is left of the front’s surface signature could get a little boost from a slow-moving mid/upper-level disturbance tracking towards us from the west. That’s why our forecast has “rain likely” for Sunday into Monday.

At the same time, a second Canadian front looks like it will be moving through the ArkLaTex by Tuesday morning, adding some additional lift and keeping decent rain chances in the forecast through Tuesday. While the first front doesn’t show any promise for cooler-and-less-humid air, the second front should provide at least a modest ‘cool down’ along with a dip in the humidity levels by Wednesday into Thursday.

Although all indications are that Nadine will be no threat to any land areas, we’re still watching this storm as it churns-up the central Atlantic. Nadine continues to be fairly-well organized, with good banding characteristics and good upper-level outflow on its northeastern and eastern flank. But as of 4pm, the NHC still has Nadine at ‘strong’ tropical-storm strength, with peak winds estimated at 70 mph. Given her appearance and a relatively favorable environment, Nadine is still expected to become a hurricane within the next day or so. If Nadine does get upgraded, she will be the 8th hurricane of the 2012 season. 

Tuesday, September 11, 2012

Humidity Returning...

By Jay Grymes & Steve Caparotta

Tuesday turned out to be another good-looking weather day and still had a touch of the fall feel, but did you notice that Gulf humidity has begun to return to our viewing area. The Tuesday morning low at Baton Rouge’s Metro Airport dipped to 61°, but we expect Wednesday’s low to by 5° to 6° warmer, a reflection of rising dew points (increasing humidity).

Wednesday’s high will approach 90° for many WAFB neighborhoods, and the southeasterly flow -- bringing in more Gulf moisture -- should assure partly cloudy skies. In fact, we think we’ll see a few blips on Titan9 Doppler by the afternoon, but they should be spotty at best: set Wednesday afternoon’s rain chances at less than 20%.

We’re going with 20% rain chances for Thursday and Friday, with scattered afternoon showers (roughly 30% rain chance) for Saturday. Highs all three days will be around 90° with morning lows in the upper 60°s to around 70° -- that will mean a summer-like feel to the air as we head into the weekend.

For now, Sunday looks like it will be the “wettest” day of the coming 7-day period with rain chances currently running at about 50% or so, but we’ll have to see how things settle-out with the forecasted cool front. Yesterday it was looking like the front would make it into Louisiana, then essentially fizzle out over the state. The latest surface charts from the NWS suggest that the front may hold together a little longer, and slowly slip southward to the coastal waters by late Monday or early Tuesday. If that happens, we’ll keep rain chances elevated for Sunday and Monday.

In the tropics, we finally say goodbye to Leslie as she heads over colder North Atlantic waters and moves NE and away from Newfoundland. And it’s goodbye for Michael as well, becoming a remnant low after being impacted by strong shear over the past 24 hours coupled with passage over cooler waters that effectively killed Michael’s convective activity.

Never fear, storm lovers -- newly designated T.D. #14 is spinning over the tropical Atlantic, and is likely to become Nadine over the next day. But the good news is that current guidance keeps #14/Nadine over the open Atlantic.

Monday, September 10, 2012

Another Beauty on the Way!

By Jay Grymes & Steve Caparotta

We’re still enjoying a taste of fall weather, but remember … this is only the “dress rehearsal.” Fall doesn’t officially begin until the 22nd of this month. In fact, a summer-like feel will start sneaking back into your neighborhood by later this week. But for the time being, let’s enjoy what we’ve got...including temps that dipped into the upper 50°s for areas north of Baton Rouge this morning!

The low will dip to near 60° for Tuesday morning here in the Baton Rouge area, with some communities north of the Capital City once again slipping into the upper 50°s. Skies will be mostly sunny for Tuesday afternoon, with a bit of a warm-up. In addition, although the air will still be reasonably “dry,” you’ll note a slight increase in the humidity as the southeast winds set-in through the afternoon. That will serve as notice that the “good stuff” is on the way out.

By mid-week, morning lows will be creeping back towards 70°, highs will be back near 90°, and you’ll know that the “fall feel” has ended. We’re putting 20% rain chances into the forecast for Thursday and Friday, with scattered rains on tap for Saturday, Sunday and Monday. Once again, Tiger fans will be watching the skies while they tailgate on a Saturday afternoon around Death Valley as our next cool front works from NW to SE across the state.

In the tropics, T.S. Leslie and ‘Cat 1’ Michael continue to spin over the north-central Atlantic -- these have been two very persistent and slow-moving storms! Leslie now looks like she’ll pass through the Canadian Maritimes ... Michael appears destined to remain over the open water.

To their south, a well-developed tropical disturbance appears to be on the brink of becoming our next system: all indications are that it will become Tropical Depression #14 later today or tonight, with a very good chance of becoming T.S. Nadine within the next 24 hours or so.