Labor Day weekend woes along the Gulf

Quick post here as my ideas on Lee and Katia have not changed much today. Lee will be around for a few days, plaguing the LA, MS, AL coastlines with heavy rain and winds that will pick up more with time. Right now, Lee is rather strung out with a max wind of 40 knots (45 mph) and a motion that is NW at 2 mph. You could literally walk in and out of the center of this storm.

Visible satellite image of newly formed TS Lee via NRL

As you can see above, Lee has taken on the characteristic of an extratropical (mid-latitude, normal) low as opposed to a tropical cyclone. An upper-low that was interacting with it has more or less induced a bit a shear and dry air, giving the half-a-storm appearance. All of the wind and heaviest thunderstorms are to the north and east with relatively nothing on the western periphery. It will be interesting to see if Lee can get its act together. Regardless, much rain is forecast for LA into AL during the next few days.

12z track guidance for Lee via NCAR
12z intensity guidance for Lee via NCAR

The track guidance is spread all over the place, but there is more agreement today on a general north to northeast wobble with time. This will spread heavy rainfall up the East Coast, something that isn’t too welcome right now. The intensity guidance is for Lee to remain a tropical storm during its lifetime (even if half a storm), but there is a slight chance it could reach Category 1 status if the center can consolidate better. Speaking of rainfall though, below is the HPC 5-day accumulation map.

5-day HPC rainfall accumulation map

This map was issued early this morning, so there might be adjustments when the new map is issued in about an hour, but you get the idea. Excessive rainfall for lower LA, mainly southeast of New Orleans, then spreading north along a frontal boundary with time.


Katia has been having quite a bit of trouble fighting off the effects of some Saharan Air and an upper-low to its northwest that is inducing 15-20 knots of upper-level shear. This does not bode well for a hurricane, hence why it has barely maintained this intensity since the 11 am advisory today.

Rainbow infrared satellite image of Katia

The satellite image above shows a distorted looking hurricane with convection showing up in more blobs as opposed to the classic looking hurricanes we typically see. Shear is to blame for this appearance. My worry is that the shear will continue to leave Katia weak, an therefore could allow for a more westward track during the next few days than currently indicated.

12z track guidance for Katia via NCAR
12z intensity guidance for Katia via NCAR

The track guidance has started to indicate a turn to the left or west in about 96-120 hours (4-5 days). This could have huge implications for the East Coast as the GFS and Euro have been trending further west with each run. The UKMET solution is rather scary as it has Katia threatening the Turks and Caicos in about 4-5 days, the furthest south of model solutions. This track would be a major threat to FL all the way to ME. The intensity guidance has been too strong on Katia up to this point as they didn’t handle the dry air and shear that have been influencing the storm’s organization. A few models still show Katia becoming a CAT 3 or 4 storm, but NHC is staying on the conservative side and forecasting a 95 knot (CAT 2 – 110 mph) hurricane by day 5. I am in agreement with them, but think the track may be a bit further south than currently indicated.

For additional imagery on these storms, feel free to visit a posting I made on the NASA SPoRT website for work today. I highlighted some new products that will be available on the new GOES-R satellite which is slated for a 2016 launch.

Side note: The possible recurvature of a West Pacific tropical cyclone (Talas) is very important to the threat that Katia may pose to the U.S. As of now, models cannot handle the interaction of Talas with the westerlies, therefore expect future forecasts to change quite a bit until about Saturday night or Sunday. I feel we will have a much better handle on Katia by then. As for Lee. . .expect that storm to stick around for a while.

I will try to post this weekend, but I will be traveling so posts might be tough. Thanks for reading!

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