Sunday Morning Update on TS Sally

September 13, 2020

I wanted to wait until the full advisory from the NHC at 10 a.m. to send out an update this morning. Sally is starting to organize but it still doesn't have convection wrapped around the center very well. Still it has 60 mph winds which isn't too far from hurricane strength. It should continue to organize and strengthen and it is expected to be a hurricane sometime tomorrow. As many of you with a weather radio or weather alerts on your phone will know, hurricane and tropical storm warnings were issued with the 4 a.m. advisory. The forecast intensity has been steadily increasing and it is now for a 90 mph storm at landfall, with the NHC noting that it may actually be a little stronger. The track has been nudged to the west a bit and now shows a southeast Louisiana landfall just after midnight on Tuesday. The forecast has the storm coming in faster now which is good because we may not see a stall over water which would bring hazardous conditions longer and add to the track uncertainty. 

Tornadoes are still a possibility but the Storm Prediction Center has yet to issue any probabilities or designate any severe weather threat areas. While no specific risk has been identified, there could be an area favorable for tornadoes along the Florida Panhandle later today into the overnight hours and we may see the outlook upgraded at some point. Right now, the SPC doesn't see much of a tornado risk tomorrow and overnight into Tuesday. Beyond Tuesday morning there may be a possibility for tornadoes but due to uncertainty in what the environment will be like no specific threat has been identified.

The latest run of the HWRF has cooled a bit on it's forecast, for the last several runs it had been showing a category 3 storm at landfall but as of the 6Z run, which ran a little after midnight, it only shows a category 1 storm. Several of the intensity models still support a category 2 storm as shown below so we'll see if this latest HWRF run is a fluke or the start of a new trend. I'm a little skeptical of this latest run but there may be good reasons for the sudden decrease in intensity, we'll see what the 12Z run shows. The Euro and GFS operational models still don't even show it becoming a hurricane, but I think they're too weak on their forecast.

The track forecast is getting more certain. It is helpful that a stall over the water looks a lot less likely, so that has tightened things up a bit regarding the possible landfall points. There is still quite a bit of spread where the storm may go beyond midday Tuesday, and that could determine where a lot of the rainfall ends up.

That's it for this morning. I think most of the Florida Panhandle can breathe easier now. LA, MS, and AL will likely be dealing with a fairly hazardous storm in a day or so. Have a great Sunday, I'll send out another update late today or tomorrow morning.

Chris