The National Hurricane Center still gives a 70% (high) chance of a low pressure area in the southern Gulf of Mexico to form into a tropical depression over the next 48 hours. The NHC hasn't pulled the trigger yet and declared it Tropical Depression 4 or Debby because it's not organized enough to be considered a tropical system.
However, conditions are still favorable across the Gulf for the system to develop into a Tropical Storm over the next few days as it slowly moves off towards the north. The area in which the system is located is low in shear, which is allowing the deep thunderstorm activity needed for a tropical system to develop.
The only major issue we have right now is A) intensity and B) strength. So, essentially, the entire forecast.
These model runs about 2 days out show the issue...
This is the 18z GFS run for the 250 mb (jet stream) level at 48 hours:
This is the 18z NAM run for the 250 mb (jet stream) level at 48 hours:
This is the 18z GFS run for the 850 mb level (about 5,000 feet up) at 48 hours:
This is the 18z NAM run for the 850 mb level (about 5,000 feet up) a 48 hours:
They don't seem too different, right? Look over the Gulf. The GFS model is showing stronger deep-layer winds across parts of the Gulf of Mexico two days out, which would steer the system off towards the northeast and into Florida. The NAM model, however, is showing much weaker winds at the same time period, allowing the storm to use its own momentum to drift northwest towards Texas.
As you can tell, that's a slight problem.
For good measure, here's what the 18z spaghetti plot of the hurricane model runs shows:
The consensus is that the system will go into Florida. However, many of the reputable models don't agree with this.
The NAM is showing the system going into Texas:
The CMC is showing the same:
And the NGP is showing it going into northern Mexico:
Note that the CMC greatly over-exaggerates the strength and that the HWRF doesn't have the thing even develop into a tropical depression.
The reason for all the model images and everything is to give some reasoning for when I say that the models are having a tough time with this system and that the forecast is very iffy at this point. They can't agree on intensity or path, which is essentially the whole forecast.
At this point, I'm tentatively thinking that it's going to drift towards Florida as a minor tropical storm, but I'm willing to be (and very well could be) wrong on that. It's too soon to tell. The system is a slow mover and there's no guarantee that it'll develop at all.
How's that for some wishy-washy forecasting for you? It's events like this that highlight that meteorology is still an inexact science and that there's a large margin of error, even thought forecasts can be eerily accurate lately. It's a safe bet that anyone on the Gulf Coast needs to keep a very close eye on this system regardless of what it does.
Speaking of which, here's the HPC's forecast rainfall over the next 5 days. This is in inches.
Either way, parts of the Gulf Coast are expecting very heavy rain over the next 5 days. Be on alert for flash flooding -- "turn around, don't drown."
I'll post another update here on DKos tomorrow, and I'll post smaller updates in the meantime over on my Facebook page.
Stay tuned to the NHC's website for the latest updates on this system.