Sunday, October 16, 2011

Long-Range GFS Tricks the Northeast with Halloween Snowfall Treat

October 30 1AM Snow Depth
Today's 18z GFS model is giving the Northeast a mean trick or treat with a 2 foot snowfall the day before Halloween. But don't fret, young trick or treaters, because this is the long-range GFS- weather speak for unreliable. While October 30th is a period where snowfall could occur in the Northeast, I have very low confidence that this will happen.

18z Models Bring Florida to Tropical Watch Status

Pre-Reading Notes: 'Tropical Watch' is a term made by The Weather Centre. This Tropical Watch was NOT produced by the NOAA, and will not be produced by NOAA unless noted.

Today's 18z models have brought Florida some dark news as both statistical and dynamical models are indicating a landfall on Florida. Here's their images, with descriptions of why they are called 'statistical' and 'dynamical'.

Statistical Models
'Statistical Models' are models that do not take into account current atmospherical conditions. In this case, the models aren't really on the favored side, but can be used in comparison against dynamical models. These statistical models show the storm forecast to impact Florida with a landfall hit.
Dynamical Models
'Dynamical Models' are models that do take into account current atmospheric conditions, unlike statistical models, and are thus more favored when looking at models. These dynamical models aren't far off from the statistical models above, but they do appear to have more of a consensus of making landfall in Central Florida.
That said, here is The Weather Centre's Forecast Graphic

Florida At Risk for Vigorous Tropical System

Florida is at Risk for a tropical system of some sort in the coming days. Below is the track and intensity plot of Invest 95L, currently on land near the Yucatan Peninsula region.
Intensity Plot

Track Plot
Several models are indeed indicating that this invest will move northeast, through the Gulf of Mexico, and make landfall on Florida's coast. The invest will then barrel through Florida and out to sea. However, I do believe that these models are underestimating the intensity. Below is current Sea Surface Temperatures in the Gulf.
One thing you may not realize is how warm these temperatures actually are. When calculating, the values are in Celsius. However, when you put in 28.5 degrees celsius (the most widespread temperature across the Gulf), you get 83 degrees Fahrenheit. This is a very warm Gulf Temperature and is actually not too far off from summer temperatures. Since no system has crossed the Gulf yet as a defined Tropical Storm or stronger, these warmer waters have not been disturbed, leaving them to wait for a new system, which may be this one. So yes- I do believe this system will develop into something of a hurricane under these conditions. I am not completely sure because of some possible over-shearing, but that remains to be seen.
This system currently has a 50% chance of development over the next 48 hours. Satellite imagery would indicate the majority of the system is over water, so let's take a closer look at some more defined imagery.
This image also shows the main convection over water and likely gathering strength at this time. That we are not sure of but seems to be a rule of thumb. Anyways, this system's models (the models tracking it) are not confident in a consensus, with some going westward ho, and others moving towards the Gulf, and still others staying somewhat stationary.

We will keep you updated on all developments with this system as they come in.