A large tropical wave near the Cape Verde Islands had been tagged as Invest 92L and upgraded to Tropical Depression Twelve and later was upgraded to Tropical Storm Katia by the NHC. Tropical Storm Katia as had excellent cyclonic turning before it even exited the coast of Africa. Katie is a well organized system, and is well is the process of developing an excellent Central Dense Overcast (CDO) and in fact is becoming more symmetrical via satellite presentation. Katia is moving at a fast clip of 20 MPH and has pretty much stayed on the 285 degree (WNW) track with a few wobbles now and then. An upper level low to the NW of Katia may, in time, become a role in the intensity of Katia, but should be a hurricane within the next 12-24 hours. The same upper level low may also induce some southwesterly shear, possibly within 96- 129 hours. At the same though, weak vertical shear and warm SST’s may be able to overcome the shear and allow further strengthening.
EDIT: As of the 11pm advisory tropical storm Katia has been upgraded to Hurricane Katia
Although it is way to early as to where Katia will be heading in the long term forecast, here are 3 trains of thought.
- Katia stays west and heads into the Caribbean and is a threat to the western Caribbean and possibly later into the GOM.
- Katia continues its WNW and either is a threat to the Lesser Antilles or is north of the Antilles and later turns NW toward the US coastline.
- Katia continues its WNW track, then NW, and eventually heads north possibly threatening Bermuda and even possibly heading into the Canadian maritimes or even recurves out to sea threatening no one.
Another fly in the ointment is an area of low pressure near western Cuba (now tagged as Invest 93L). That area possibly may develop into a tropical cyclone. This may have implications as to where Katia may head later in the forecast period.
Scenario 1 where Katia stays in the Caribbean, has a very low chance, maybe 10% and thats being generous. Katie is already at 14.4 °N latitude and slowly gaining. Unless something drastic happens, I just can’t see that scenario 1 will ever play out, but I don’t want to rule it out.
Scenario 2 where Katia possibly threatens the Lesser Antilles or is 100 miles north of the islands, this has maximum of a 30% chance. If Katie has not made the turn from WNW to NW then this scenario might happen. The trough that is forecast is either to weak or pulls out early, this may allow Katia to head a little further west than forecast. It also is dependent on that area of low pressure in the southern GOM has developed into a tropical cyclone or not (I will allude to that later).
Scenario 3 – recurving and not hitting the eastern coast of the US but possible impacting Bermuda. This scenario has the highest chance – 60% chance. At this moment, most of the models are very much in agreement. Katia should begin to turn to the northwest and eventually turn north because of the trough that will situated over the eastern US by Monday of next week.
Assuming that scenario 1 is out of the picture , lets visit the area of low pressure in the southern Gulf (93L).
In the Eastern Pacific, the western Caribbean and into the southern GOM, along with an old frontal boundary that runs along Florida to the western GOM, a surface low may be trying to form possibly to the north of the Yucatan. Some models are supporting this and this may head NW toward the Texas area. The oceanic heat is very warm in this area (in some areas, 30°-31° Celsius) and a depression or tropical storm (Lee) most likely will develop. The ridge over Texas is still strong but a shortwave trough might have enough punch to create a weakness in that ridge in a few days. As the trough gets closer to Texas, this may cause the 93L to stall or drift for a few days. Even if this system does not have “landfall” in Texas, this may create enough rainfall to help the relief in that area.
Back to Katia, and scenarios 2 and 3. If 93L develops to become a named storm “Lee”, then a ridge would be in place in the west central Caribbean. With 93L in the Gulf, Katia in the Atlantic and the ridge between the two, this would be enough to force Katia northwest and should keep Katia from the eastern coast of the US or at least the southeast coast.
Again, this is just a long term forecast – which ever scenario plays out – all of them will have changes in them. As always, remember to always use the official information from your local NWS and the NHC.