Tropical storm or hurricane increasingly likely into Louisiana this weekend.

Discussion:

While the system has only become slightly better organized overnight, it has gained enough organization to be upgraded to a tropical storm. Satellite images this morning show a rather disorganized system with some banding, but a difficult to locate center compared to yesterday. The low level center is likely on the western edge of the limited deep convection and not far off the coast of Nicaragua.

Track:

As mentioned yesterday evening there was significant track differences between the GFS and ECMWF much of which was hinging on the amount of high pressure that would build east of FL this weekend. Overnight the ECMWF has come into much better agreement with the GFS of much more significant ridging off the FL east coast. There is now much better agreement with the GFS, ECWMF, CMC, and UKMET all showing a NW to NNW track through the NW Caribbean Sea, the central Gulf of Mexico and toward the Louisiana coast. As the ridge off the FL east coast intensifies this weekend, Nate will begin to accelerate rapidly toward the NNW. Nate will enter the Gulf early Saturday morning and rapidly move NNW toward the Louisiana coast making landfall in just over 24 hours (Sunday AM) after entering the Gulf. Once Nate arrives in the Gulf of Mexico Saturday morning, there will be little time for preparation.

Intensity:

Given the slightly westward adjustment of the short term forecast track…this results in more land interaction with central America and the NE Yucatan. While conditions will be very favorable over the western Caribbean Sea for development, it will take time for the inner core of Nate to develop once the system leaves central America. Once in the Gulf of Mexico, Nate will be moving very rapidly which will likely help to prevent significant intensification as the time over the warm Gulf waters will be limited. Most of the intensity guidance has trended downward overnight, but NHC still brings the system to a 75mph hurricane before landfall over Louisiana Sunday morning. It is interesting that the latest GFS brings Nate to the LA coast as a weak tropical depression.

The intensity forecast is of low confidence.

It is too early to discuss impacts to the central US Gulf coast, but the area of SE LA and coastal MS is extremely vulnerable to storm surge. Additionally, the expected rapid forward motion will bring strong winds well inland along the forecast track of the system.

SE Texas Impacts:

At this time no direct impacts from Nate are expected over SE TX however any additional shift of the forecast track westward would potentially bring impacts to our eastern areas this weekend…especially the marine zones. Tides are already running near coastal flood criteria and NE winds on the western flank of the circulation will likely keep these tides elevated into the weekend. Additionally, long period swells will generate outward away from the center of Nate and will likely begin to arrive on the upper TX coast late Saturday which could also result in slightly higher elevation of the tides.

While not directly connected to Nate, a non-tropical area of low pressure over the FL Keys this morning will race WNW across the Gulf of Mexico today and Friday and approach the upper TX coast late Friday and Saturday. This may help to increase rain chances depending on if/how much the larger circulation of Nate tries to steer the system WSW over the NW Gulf. At this time, the GFS does show a few of Nate’s rainbands nearing SE TX Sunday into Monday, but I am not sure these bands will extend this far west at the moment.

TD 16 becomes a tropical storm over the SW Caribbean Sea

TD 16 becomes a tropical storm over the SW Caribbean Sea