KATC StormTeam 3 Weather BLOG

A couple of weeks ago we started talking about increased activity around the beginning of August, and as expected, the tropics are heating up…right on time.  Tropical Depression #3 was upgraded this morning to Tropical Storm Chantal.  Satellite imagery indicates that the intensity is now 40mph, allowing it to have a name.  Chantal should continue a rapid Northeast movement over the colder waters of the Atlantic, possibly brushing the Atlantic Provinces of Canada.  This area from the east coast to Bermuda to Greenland looks to get quite active over the next couple of weeks as a series of fronts move off the US mainland.

Another disturbance near the Windward Islands bears watching too.  Right now the disturbance is surrounded by very dry air and some Saharan dust is in the mid and upper levels preventing development.  As the wave moves across the islands, low wind shear, higher humidities, and less dust intrusion should give it a boost in the Caribbean.  Most early models suggest this system, whether it develops or not, should continue on a westward track toward Central America.

 Local weather will stay a bit unsettled today through Thursday as a weak front stalls near the Gulf Coast.  By Friday, the front will wash out, and high pressure will re-build.  Over the weekend we will start dropping the rain chances, but boosting the temps back into the mid 90s.  Heat index values may reach 105 by Sunday.

Fewer storms today translated to hotter afternoon temperatures with highs in the low-mid 90s area-wide. Heat indices reached into the lower 100s and I would expect more the same tomorrow.  We should see a better chance scattered showers and storms tomorrow afternoon.  Higher rain chances will be likely Wednesday and perhaps Thursday in response to a weakening and stalling frontal boundary.  Although I wouldn’t be looking for a cool down, slightly drier and more stable air should arrive from the northeast for Friday into the weekend with highs pushing back into the low-mid 90s this weekend.  Rain chances will still be in the forecast but they should be in the slight category Friday through Sunday. 

As I alluded to last week, tropical waves in the Atlantic are beginning to look more like tropical waves should this time of year.  There will probably be some development over the next few days with one or two systems.  One disturbance is about 850 miles east of the southern Windward Islands while the other is closer to the African coast.  The NHC began running model runs on the wave east of the Windward Islands which means they are anticipating some development too. Visible satellite imagery this afternoon revealed a good signal for at least mid-level cyclonic turning so in the next day or so we may be talking about a depression.  The other wave near Africa already has surface low pressure attached to it so if the system can survive some dust to the north, it too will have a chance for development later this week. Don’t forget to tune in tonight at 10pm for more on “Louisiana’s Most Notorious Hurricanes”.

Another hot and humid day around the regions with scattered showers and thunderstorms popping up later this morning and early this afternoon.  We have an old frontal boundary that sag toward the Gulf coast keeping the weather a little more unstable for the early part of the week.  By Thursday or Friday the front will dissipate allowing for high pressure to re-build.  Dry weather will return for the weekend, but temps could reach the mid 90s.

 We have  a disturbance in the Atlantic a couple of hundred miles west of Bermuda.  Upper level conditions may become more favorable this week for this to develop, but at this time it is no threat to the Gulf coast.  Models are showing a couple of more disturbances over the next two weeks, a sure sign that August is almost here.

This afternoon turned out to be a gloomy one with heavy rain off and on. The deep tropical moisture will continue through Sunday before the upper low drawing it in will move west. That will allow for an area of high pressure to bring in slightly drier air and we will be back to the typical summertime showers and storms by Monday. We could pick up on another inch before the lower rain chances come. Not much seems to change through the work week.

In the tropics, there is an area of showers that has formed northeast of the Bahamas. It looks very disorganized but it may develop in the next couple of days. It is expected to continue moving northeast meaning it will stay in the Atlantic so at the time it is not a concern to the Gulf. Else where it’s quiet in the tropics and lets hope it stays that way.

As expected plenty of on and off tropical showers have soaked the area today with more of the same expected tomorrow.  Weak areas of surface low pressure had developed along the upper Texas and Southwest Louisiana coasts but they have been weakening this afternoon as they have been moving inland.  The threat of heavy rainfall will continue tomorrow but should shift a little closer to the upper low that is situated in Texas by Sunday.  Nonetheless with all this deep tropical moisture I would expect high rain chances to continue for tomorrow with locally heavy rainfall amounts of several inches possible in spots.  Showers and storms will be likely again Sunday but we should see a few intervals of sunshine thrown in.  Rain chances should stay above normal through early next week with perhaps another backdoor front proving some relief at least in the rain chance department for mid-late next week. 

As for the tropics, a couple of tropical waves in the Central and Eastern Atlantic are showing some signs of organization, but no developments are expected in the near term.  But I will say that the waves are starting to look a little beefier…right on time.  As for the Gulf, this current system will continue to move inland but with continued upper “troughiness” in the Eastern Gulf I wouldn’t be surprised if another weak disturbance develops there by early next week. 

One interesting observation of the weather today…you may have noticed that the rainfall droplets are markedly smaller than what we usually see in a thunderstorm, but the density of drops per cubic area is much higher.  This translates to us getting really wet when it does not seem to be raining that hard…believe me, you notice this more if you are bald!  This is typical of purely tropical systems.  Hopefully you will observe this, especially when the wipers are clearing the windshield on your car.  Tune in tonight at 10pm for the latest on our tropical rains, plus check out the “Notorious Hurricane” I’ll be highlighting, the deadliest storm in Louisiana’s infamous hurricane history.

Plenty of moisture in the Gulf will return to Acadiana in the form of rain and thunderstorms.  Some of the rain may get heavy for a while.  Coastal sections may see up to 3 or 4 inches of rain, while the rest of the Acadiana area will see an average of 1-2″.  Low pressure at the surface will roll inland into Texas, so the threat of a tropical system developing appears to be less likely.  That low combined with a ridge of high pressure over Florida will squeeze the pressure gradient over Louisiana.  Winds will increase to the 15-20mph range, and more Gulf moisture will ride in on that strong southerly flow.  The low will fill in late Sunday, so rain chances will go down by the end of the weekend.  The tropics have been quiet, which is typical for July, but usually we start to pick up more activity in August.  Some of the models are hinting that things will be getting more active after the first full week in August…stay tuned and stay dry!

Lots of tropical moisture will continue to get funneled toward Acadiana as an upper low in Texas in conjunction with an area of disturbed weather in the Gulf of Mexico will keep us cloudy and wet.  There will be a heavy rain/flood threat over the next few days but pinpointing who will get the worst of it will remain a quagmire.  I looked closely at buoy, ship and offshore platform data and Quickscat satellite estimates and they all point to some surface troughing in the Western Gulf, but no closed low pressure.  The pressures have remained fairly high and upper level winds remain hostile to tropical development.  If this feature persists offshore through Saturday then we may be looking at it more closely.  So the bottom line for now is that expect several waves of shower and thunderstorm activity with high rainfall chances over the next several days.  Rainfall amounts through Sunday will likely total 2-3 inches in most sports with isolated totals likely to exceed 5-6 inches.  The best bet for a potential flooding rain event would be back into Texas closer to the upper low, but as long as remain in the deep tropical plume of moisture we could see locally very rains from time to time at least through Saturday.  I’m keeping rain chances high into early next week as even though the upper low should retrogress to the west with time, the tropical moisture will remain locked in.  In addition, there may be a weak backdoor front trying to come in for early next week which may keep us rather wet until mid-week.  Thereafter higher pressure and more stable air should move in lowering our rain chances and upping the temperatures back into the 90s for later next week.

Scattered rain came back as winds shifted out of the south ushering in moist air. It still looks like a heavy rain event possible through the next few days as an upper low over Texas draws in more instablility from the Gulf. Not only that but an area of low pressure in the Bay of Campeche could possibly spread more rain our way early in the weekend. So we enjoyed the sunny weather but now we must pay the price.

The low in the southern Gulf really doesn’t look too impressive and upper level winds are still quite strong. But that doesn’t mean this system can’t develop and we can stop watching it. Hurricane Andrew developed very quickly despite strong wind shear. I don’t want to seem pessimistic but you should just stay tuned for the latest. It is hurricane season after all.

After this weekend we should return to the pattern of sea breeze showers and storms each day through the rest of the forecast.

Already this morning showers and storms are lining up along the coast and some will move inland this morning.  A few pop up storms are possible this afternoon along the I-10 corridor and northward to about US 190.  Northern parts of Acadiana will probably stay dry today, but get ready for widespread rains Thursday and Friday.  Low pressure developing near the lower Rio Grande Valley will pull the moisture out of the Gulf bringing heavy rain to much of coastal Texas, and scattered heavy rain to Louisiana.  Rainfall amounts will probably stay less than 1/2″ today, up to 1″ Thursday, and between 1-2″ for Friday.  As the low drifts westward over the weekend, the rains should stay mostly to the west, but as the rain chances go down, the temps are back up for Saturday and Sunday.  Highs will reach the low 90s with the heat index back to near 100 most of next week.

Changes are on the way as plenty of tropical moisture has been pooling in the Gulf and is expected to begin surging northward tomorrow.  So expect higher humidity tomorrow, more clouds developing throughout the day, and scattered showers and some thunderstorms tomorrow afternoon.  Activity will become more widespread for Thursday and Friday as a weak upper low over Texas will keep the tropical moisture conduit pointed at Louisiana for several days.  There shouldn’t be any one area where there will be a focusing mechanism for major flooding rains, however, there will be the potential for an inch or two of rain each day into the weekend so areas that see repeated storms could get quite soggy.  What makes this pattern more interesting and perhaps very wet is that a tropical wave that is pushing into the Bay of Campeche will get drawn northward in this pattern.  The root of the axis of this wave connects southward through Central America and into the Pacific so the draw of tropical moisture could be potentially quite deep.  When this happens someone usually winds up with a 10 inch plus rainfall…but that could happen anywhere from Texas to Mississippi so we’ll keep an eye on this. 

Speaking of the tropics, we’ll keep an eye on the wave entering the southern Gulf…development is not out of the realm of possibility.  Another tropical wave was noted in the Central Caribbean while the rest of the tropical Atlantic remains under the influence of dry and dusty air from the Sahara.  This dust can really knock down on the tropical development process, but most of the dust has been dissipating by the Central Caribbean, so the tropical hot spots over the next few weeks will likely be the western Caribbean and the Gulf…provided upper shear decreases, which it should as we head into August.   Hopefully the dusty pattern will continue for 10 more weeks, but that is just wishful thinking.