Saturday, August 04, 2012

Ernesto's Hanging In There

Ernesto has survived the past 36 hours rather well and is a strengthening tropical storm in the Caribbean that sports 60 mph max winds as of early this morning. Ernesto has been able to intensify somewhat due to the help of a strong upper level trough that dug down to Ernesto's east in the Atlantic. The trough is helping to provide a bit of an outflow channel to the northeast of Ernesto, allowing for some strengthening in an area where tropical cyclones don't fare too well historically. Ernesto's environment is pretty decent on the whole -- shear is generally low over the storm, the Caribbean is warm, and outside of some dry air to its west that seems to be riding along in the low level flow, Ernesto probably does not have many challenges ahead of it over the next few days.   A hurricane classification by tomorrow is pretty realistic for expectations...and from there, it's a matter of where Ernesto goes  and how strong the storm can get.

Model spread suggests anything from a split of the Yucatan and Cuba (GFDL, the more aggressive scenario on strength) and a Belize hit.  Ernesto will not maintain a due west heading, gradually pulling itself a bit more north of due west over time before bending more WNW or even NW towards Tuesday as it feels a bit of a weaker mid level feature tracking through the Southern US...a possible piece of energy breaking away from the trough that crosses the Northeast on Sunday & Monday with our thunderstorm threat here.  This could provide enough of a tug to bring Ernesto up to the NW.  The stronger Ernesto gets, the more likely it is to be tugged by that Southeastern US weakness and get pulled more north as it trucks west.

Ernesto should intensify into a hurricane before first landfall, with a good chance of becoming the season's first major hurricane -- and the risk for landfall runs anywhere from a clipping of Honduras before hitting Belize (not likely) to the upright split...the most likely zone is somewhere in the Yucatan on Tuesday night into early Wednesday. From there, trajectory suggests either Mexico (if a more southern track holds) to a US hit if the storm splits the Yucatan/Cuba uprights. This will not come up the East Coast,'s a Gulf hit if it hits the US.

Farther out, the blob of storms on the far right of this satellite is Tropical Storm Florence, upgraded as of 8 AM after being declared a tropical depression just last night. It will run into that trough in the Central Atlantic that is helping Ernesto...and Florence will probably have a tough time surviving that trough should it traverse into it in three days' time. Until then, it'll be satellite eye candy.

You can track Ernesto's progress over the next few days on our "tropics tracker" page.