Tropical Storm Katia
TD #12 strengthened overnight and is now Tropical Storm Katia with 45mph winds as of 11am. The storm is looking much better organized today with nice curved bands and good outflow. Katia is well on her way to being a hurricane likely within 24 hours and probably a major hurricane in 60-72 hours.
Katia will continue to move WNW over the next several days and as of now all model guidance I have seen takes the storm northeast and north of the northern Leeward Islands. This will occur as we see a trough amplify off the northeast coast this weekend weakening the eastern flank of the subtropical Atlantic ridge.
The big question of course is whether Katia will every eventually threaten the US. Right now, almost all the guidance says no. There are some members of the 00z ECMWF ensemble and the 12z GFS Ensemble that show a rather close pass to the US east coast, but most keep it safely off shore as it re-curves. This is because most all of the ensemble guidance wants to develop a significant trough over the eastern US in about 7 days that would turn Katia out to sea. Right now, this is well supported in the model guidance (including the 12z suite today) and fits the overall pattern we have seen the last 2-3 weeks of more troughs in the eastern US. Of course this can change since the major players will be traversing the Pacific Ocean and will be better resolved once they move ashore.
So right now keep up with Katia, but the signs are not as ominous as they were with Irene.
Gulf of Mexico
A tropical wave in the western Caribbean will move into the Gulf of Mexico in the next 24-48 hours and the NHC has designated this as a 10% threat area. The 00z models were rather bullish with this system turning it into a strong tropical storm impacting Texas. The 12z guidance is not nearly as strong but do produce a weak long lasting system in the Gulf that would bring much needed rains to Texas coastal areas.
I think the best course of action with this is to predict modest development in the next 72 hours with the system possibly becoming a depression or Tropical Storm Lee in the next few days. Since it will be in the Gulf where the waters are very warm it will have to be watched very closely. It could bring some much needed rains to areas of Texas. It could also linger for several days as it will be near an upper ridge over the southern Plains safely potentially tucked away from troughs moving to its north.
This could end up being a bigger threat to the US than Katia, but we will have to watch it.