Possible severe weather for Mid-South today

Yesterday, parts of the area got a taste of how tropical remnants can produce severe weather, particularly tornadoes. As was the case yesterday afternoon near Oxford, MS, these funnels and tornadoes are usually weak, however they are still tornadoes and can still do damage. They also don't get produced from the same types of tornadic storms we are more familiar with in these parts - those of the supercell or squall line variety. While supercells may have storm tops that extend to 40-50,000 feet plus, tropical remnants are more low-topped (25,000 feet or so), but due to the strong to extreme wind shear that exists in these systems, funnels and weak tornadoes are easier to come by.

Today, we are under a SLIGHT RISK of severe weather with the greatest threat being from weak tornaodes this afternoon and early evening that would might be produced by any stronger showers and t'storms that form in banding structures that rotate around the center of the storm. Continue to keep a weather eye to the sky as the day progresses and visit MemphisWeather.net for the latest on the severe weather threat.

Reporting on Gustav, as described by Washington Post

Great article by Paul Farhi of the Washington Post, as published in AlabamaWx.com's blog. See the article here: http://www.alabamawx.com/?p=10515 Thanks to AlabamaWx for bringing this one up!

Remnants of Gustav to affect Memphis area

As Gustav's remnants move into northwest LA and, overnight, eastern TX, rains from the storm are pushing closer to the Memphis metro area at this time. Look for fairly high rain chances for the next 48 hours, though the edge of the precipitation will be fairly well-defined, so some areas will see decent rain, while others will remain dry within several miles of each other. In addition to the rain, showers will also produce gusty wind and some thunderstorms will also form along the edges of the precipitation. A few of these storms could produce weak tornadoes due to the high degree of wind shear in the environment, which is typical with landfalling hurricanes. In fact, at press time, a couple of tornado warnings (with one confirmed spotter sighting of a tornado) are in effect for portions of northwest MS. Keep your weather eyes and ears open the next couple of days!


Elsewhere, T.S. Hanna is lingering over the southern Bahamas and is expected to start a NW track by tomorrow, paralleling the FL east coast then making landfall late in the week along the GA, NC, and SC coastline. Ike is moving steadily across the central Atlantic and is due in the Bahamas this weekend and Josephine has formed today in the far eastern Atlantic and is strengthening as it moves west as well. The Atlantic Hurricane season is in full swing!!

Landfall

Hurricane Gustav officially made landfall at 9:30am CDT (1430 UTC), Labor Day, September 1, 2008 near Cocodrie, LA, about 70 miles southwest of New Orleans or 100 miles southeast of Lafayette, LA. Intensity of the storm at landfall was Category 2 with 110 mph wind and central pressure of 955 mb (28.20 in). Radar from New Orleans and visible satellite image at time of landfall are below. Gustav will slowly weaken the next 6-12 hours, then weaken more rapidly as it slows considerably over western LA/eastern TX. Be sure to visit the MWN Tropical Page for more details.

Gustav Update - 8:00am CDT Monday

Gustav is about to make landfall south of Houma, LA at 8am. A radar image from New Orleans at 7:53am CDT is shown above. Gustav failed to increase in intensity overnight and satellite presentation remains ragged with no real eye present (in fact the hurricane hunters even failed to identify an eye). The Hurricane Center drops the storm to 110 mph at 8am - a category 2 storm. I find it odd that a storm without a definite eye (for hours now) and one that all sampled data (like dropsondes, flight level sampling, and satellite estimates) would indicate as a slightly weaker storm, would still be a major hurricane up until 2 hours ago, then it is dropped to category 2 right before landfall... This is what people will remember and how it will be written in the history books - a Category 2 storm that just missed New Orleans.

Given all that, Gustav is still an extremely dangerous storm. Storm surge will be an issue along the southeast LA and MS coastlines. New Orleans should not see the same issues with levee failure and surge that they saw with Katrina since the storm's path will not be pushing water out of the Lake into the city, but very heavy rain could still inundate portions of the city. Obviously, wind damage and flooding rains will be a major issue. Up to 6-12" of rain can be expected across LA, southern MS, and southern AL, with even more expected for western LA and eastern TX as the storm stalls over this area in the coming week. We'll still be talking about flooding in these areas a few days from now. Hurricane-force wind will be felt across southern LA and into central LA as well, and tornadoes are possible east of where the storm makes landfall, including southern MS and AL, the FL panhandle, and southeast LA.

Sunday mid-day Gustav update

Woke up this morning to find that Gustav is yet another example of why it is so hard to forecast hurricanes, even when the factors seem to be fairly well known. After crossing Cuba, Gustav has not (yet) been able to get it's act back together as well as we thought this time yesterday. The storm structure is somewhat ragged with an elliptical eye all but obscured on satellite, dry air is beginning to wrap into the storm, and upper-level shear is starting to increase slightly. In addition, it's pretty much over the most favorable water it will encounter between now and landfall.

Given all this, Gustav is still powerful and impressive in size. Tropical storm conditions can be felt as far away as 200 miles from the center, meaning these conditions will begin affecting the immediate Gulf coast overnight tonight. The NHC is predicting landfall by early afternoon tomorrow (Monday) along the central Louisiana coast as a major (Cat 3) storm. Hurricane Warnings are posted for the LA, MS, and AL coastlines and the entire city of New Orleans is under mandatory evacuation. Here in Memphis, Amtrak is bringing up to 3,600 NoLa residents to shelters until the storm passes. Seems federal, state, and local agencies are being a little more proactive this time around after the disastrous response to Katrina.

The track of Gustav is the one thing that has changed little, at least through landfall. It is still expected to quickly move over the south-central LA coast tomorrow and then slow fairly dramatically Tuesday as it turns WNW or W towards west-central LA and eastern TX. The track beyond about 48 hours is difficult to place as models are having a hard time with a slow-moving Gustav. With a more westerly track into TX favored, this would mean lower rain chances for the Mid-South, but I do expect we'll see enough cloud cover to hold down daytime temps during the first half of the week. In fact, cirrus clouds along Gustav's outer periphery are already encroaching on the area and a steady easterly wind will pick up tomorrow. Look for scattered showers and t'storms for possibly a good portion of the upcoming week, depending on the track of Gustav's remnants.

I have posted a new Tropical page on MemphisWeather.net that you will want to check out that has the latest satellite and radar imagery, forecast tracks, and Hurricane Center bulletins. Find it here or go to MemphisWeather.net and click the link on the front page.

Gustav goes nuts

As expected when I last wrote and predicted by the models (though not to this extent), Gustav broke free from Jamaica, hit the deep warm waters of the Caribbean where very little wind shear exists, and exploded. The storm went from minimal Cat 1 at 3:15pm yesterday to strong Cat 3, now with 120 mph sustained wind! The official forecast calls for additional strengthening to about Cat 4 as it reaches western Cuba. This will be a devastating storm for western Cuba, including the Isle of Youth, where up to 2 feet of rain is possible along with a storm surge of 14-19 feet near the center of the storm. This morning's radar imagery from Cuba, as well as the first visible satellite shot of the morning over the Gulf, taken at 7:15am, is shown below.




The projected path of the storm continues to take it into the southern Gulf as a major Cat 3 storm by tomorrow. As it approaches the U.S. mainland, the uncertainty starts to rise in it's track and intensity. Regarding intensity, while conditions remain optimal through tomorrow, by Sunday night, shear is expected to increase and the waters actually cool slightly, which both could promote a slight weakening by the time it reaches the northern Gulf. Also, history tells us that storms just don't maintain "monster" status for an extended period of time - conditions don't stay that good for more than a day or so. Should Gustav reach Cat 4 or even 5 (which is not out of the question), I'm not sure with the conditions I mention above that it will be able to maintain that all the way to U.S. landfall. (Not that a Cat 2/3 storm is anything to take lightly of course, but total devastation would not be as likely).

As for the track, models continue in two camps, though one or two are starting to take on traitor status and jump from one to the other. Some continue to move Gustav directly northwest with landfall along the central Louisiana coast Monday night (which the Hurricane Center still is going with). But many are now indicating the high over the Great Lakes will not only shift the track left, but slow the storm down and then bend it back to the southwest after making landfall (or even before landfall according to a couple of models), increasing a flooding risk for eastern Texas and Louisiana by the middle of next week. See the track map below. In any case, it does now appear that the high pressure over the eastern U.S. will have a strong impact on Gustav and significant flooding could be a major part of this storm's history when all is said and done. We'll continue to monitor.

Hurricane Gustav takes aim at Gulf Coast

As of this afternoon, Gustav has once again reached Hurricane status, increasing to 75 mph as it continues to expand into an increasingly large storm. After passing over Jamaica early today and weakening slightly, it now heads for the Caymans, then turns northwest with one more small obstacle in its path - eastern Cuba. This portion of Cuba is fairly narrow and should not have a great effect on the storm. Forecasts point to the likelihood of a major hurricane (Cat III)as it heads across the Gulf of Mexico Sunday and Monday for an eventual landfall on Monday night or early Tuesday. On it's current track, landfall is expected along the Louisiana coastline, however this far out, the margin of error is still large enough that everyone from Houston to Pensacola should be prepared for at least tropical storm, if not stronger, conditions.

Tropical storm conditions will start to be felt as early as Monday morning along the coast ahead of the storm. Evacuation orders are already in place or take effect tomorrow for many locations, including the city of New Orleans, where today they commemorated the landfall of Hurricane Katrina 3 years ago to the day. We can only hope that Gustav does not inflict the magnitude of damage that occurred with Katrina and that emergency and government officials are more prepared than 3 years ago.

Below is the current forecast track from the Hurricane Center as well as a plot of most of the computer models' forecasts indicating the degree of error that still exists - the spread lies all the way from Houston to New Orleans. The big question mark seems to be the strength of a high pressure system due to be over the Ohio Valley early next week - a stronger high would tend to steer the hurricane further west (which some models are forecasting) while a weaker high will allow the storm to continue on a due northwest track closer to New Orleans, which others are forecasting will happen. Only time will tell.

Though this storm will get all the press for the next several days, strengthening T.S. Hanna in the Atlantic also bears watching as it too could affect the U.S. mainland later next week.