BREAKING: Tropical Storm Isaac Forms

Reconnaissance data from aircraft investigating Tropical Depression NINE have sent back information that shows many instances of tropical storm winds being observed, including one wind speed calculated at 44 MPH.

This means that the next National Hurricane Center update will most likely certify this as Tropical Storm Isaac. I will have an evening post up and out later on.

Andrew

BREAKING: ECMWF Bombs TD-NINE Into Major Hurricane in Gulf of Mexico

The fresh-off-the-presses 12z ECMWF has shown a Category 3 major hurricane swirling in the Gulf of Mexico, with a central pressure of 961 millibars- and it's still offshore.
This comes as the models begin to split up on a solution. Now that the ECMWF is sending a major hurricane into the Gulf of Mexico, time will only tell how the next model suite reacts to this news.

Andrew

Tropical Depression NINE Forms in Atlantic

Tropical Depression NINE has formed this morning over the Atlantic out of Invest 94, beginning the process that could land this system anywhere from Texas to Nova Scotia at any strength you can think of. Below is the latest model spread.

The latest 12z model spread is split, but a general consensus keeps the system going on a mainly westward track before curving north and threatening Florida. Which side it threatens remains a question, and that will largely depend on how weak/strong it becomes over the next 24-48 hours. Let's look at the observed track to see recent trends.

The latest trend in Tropical Depression NINE's track is a west-southwest movement, which bodes well for a threat to the Gulf Coast. Now, this threat is not too great to begin with (unless a southwest motion begins), but a Florida threat increases with every motion to the west or west-southwest. Typically, systems above the 10 N line will recurve and go either out to sea or threaten the East Coast. Whether that happens remains to be seen.

Andrew

Past track and forecast tracks from UW-Milwaukee

Invest 94 Poses Serious Threat To Gulf of Mexico

I have looked at a lot of data this evening and have come to the conclusion that the Gulf of Mexico is indeed at risk from Invest 94, soon to be Tropical cyclone Isaac.

Above is the steering flow at 250-850mb. The steering flow is like seeing a current of water in a sink take a small object and move it around within that current's reach. The steering flow shows where storms may go by identifying wind patterns at different levels of the atmosphere.
In the above chart, we recognize Invest 94 at 40W in longitude, and is shown as a blob of yellow and orange. At the moment, this is not the ideal chart, but if/when rapid strengthening occurs, this is the chart that model forecasts indicate should be used.
If we were to use this to give a rough estimate on the possible track of Invest 94, I could easily see it drifting west and following the band of winds that cuts through the Caribbean. However, the system would likely stay north of the full extent of the current, opting to enter the northern Caribbean and continue west, as model guidance is in agreement with at this time.

This map is the 0 hour analysis (not a forecast) of the Atlantic Ocean in the 500mb heights, with added MSLP. We can see Hurricane Gordon to the upper right corner of the image, which is moving towards Europe. But notice the massive high pressure regime in place across the Atlantic. This is a primary reason why I believe the new model trend of westward motion is right and why the Gulf of Mexico is at risk.
As many of you know, high pressure systems spin winds in a clockwise formation, while low pressure systems go counter-clockwise. This clockwise motion of winds would keep Invest 94 in the southern part of the Atlantic and move it towards the Caribbean. Typically, we will see a a few cracks in between high pressure systems, and these cracks will shoot the invest north. However, now that there are multiple high pressure systems, there are next to no cracks for the system to break through and move north.

I am having a feeling that the Gulf of Mexico is indeed at risk on this. I have not had much success with when I use my instinct on weather events like this, but current and forecast atmospheric conditions, combined with the strength and steering flow of the system tells me that a westward motion will continue with this system, and westward enough to put the Gulf of Mexico on alert.

I decided to run the Tropical Cyclone Forecasting (TCF) Model for Invest 94 at this time, only for track and not intensity.
You can find the TCF's Home page by clicking here.

TCF 7:00 PM Run

Andrew

GFS Smashes Hurricane into Texas in Late August

The latest 12z GFS is projecting a landfall of a hurricane right into downtown Houston, Texas at the very end of August.

Yesterday, the 12z GFS also showed a major landfall of a hurricane on the East Coast. Now, the wide variability of the track is not reassuring, but I am seeing a trend of a system threatening the US. As of now, there is nowhere near a track, but when you get a few scenarios within several runs where a major event happens within a certain range, it usually means something.

Because Invest 94 (the system that would be responsible for this) has begun a westward trend rather than a northwest trend, this track would seem like an OK solution. However, the GFS is known for being deliberately too strong and too fast with tropical systems, so take this for what it's worth.

Andrew